TRB PG Assistant - Arrays - indexed and associative arrays, looping arrays, array operations Online Test (MCQ Quiz)

1. What is the primary purpose of arrays in PHP?

A) To store single values of different data types. B) To store multiple values of the same data type. C) To store multiple values, accessible by an index or a key. D) To define functions and methods.

2. In PHP, how are indexed arrays typically created?

A) Using key-value pairs like 'name' => 'John'. B) By assigning values to specific numeric indices. C) Using the associative array declaration syntax. D) By calling a predefined array function.

3. Which of the following is an example of an indexed array declaration in PHP?

A) $colors = array('red', 'green', 'blue'); B) $person = ['name' => 'Alice', 'age' => 30]; C) $numbers = '1, 2, 3'; D) $data = new ArrayObject();

4. What is the default starting index for an indexed array in PHP?

A) 1 B) 0 C) NULL D) The first element's value

5. How can you access an element in an indexed array in PHP?

A) Using a string key, e.g., $array['key']. B) Using its numeric index within square brackets, e.g., $array[0]. C) Using a dot operator, e.g., $array.0. D) By iterating through the entire array.

6. What distinguishes an associative array from an indexed array in PHP?

A) Associative arrays can only store strings. B) Associative arrays use named keys (strings) instead of numeric indices. C) Indexed arrays are always ordered, while associative arrays are not. D) Associative arrays cannot be looped through.

7. Which syntax is used to declare an associative array in PHP?

A) $ages = [10, 20, 30]; B) $student = ['id' => 101, 'name' => 'Bob']; C) $fruits = 'apple', 'banana', 'cherry'; D) $matrix = array(array(1, 2), array(3, 4));

8. If you have an associative array like $config = ['host' => 'localhost', 'user' => 'root']; how do you access the username?

A) $config[0] B) $config['username'] C) $config['user'] D) $config.user

9. What is the result of printing an array directly using `print_r($myArray);`?

A) The first element of the array. B) A JSON representation of the array. C) A human-readable representation of the array's structure and content. D) An error message.

10. Which PHP construct is commonly used to loop through all elements of an array, regardless of whether it's indexed or associative?

A) A traditional `for` loop. B) A `while` loop. C) A `foreach` loop. D) A `do-while` loop.

11. What does the following `foreach` loop do: `foreach ($array as $value) { echo $value; }`?

A) It iterates through the array and prints only the keys. B) It iterates through the array and prints only the values. C) It iterates through the array and prints both keys and values. D) It prints the entire array as a string.

12. How can you access both the key and the value during a `foreach` loop in PHP?

A) Using `foreach ($array as $key) { echo $key . $value; }`. B) Using `foreach ($array as $key => $value) { echo $key . ': ' . $value; }`. C) Using `foreach ($array as $key, $value) { echo $key . ' ' . $value; }`. D) It's not possible to access both simultaneously in a `foreach` loop.

13. Which function can be used to add an element to the end of an indexed array?

A) array_unshift() B) array_push() C) array_splice() D) array_merge()

14. What is the purpose of `array_unshift()`?

A) To remove the last element from an array. B) To add one or more elements to the beginning of an array. C) To combine two arrays. D) To sort an array in reverse order.

15. Which function is used to remove the last element from an array and return its value?

A) array_shift() B) array_pop() C) unset() D) array_slice()

16. What does `array_shift()` do?

A) Removes the last element of an array. B) Removes the first element of an array and returns it. C) Removes a specific element by its key. D) Removes all elements from an array.

17. Which function is used to remove an element from an array by its index or key?

A) array_pop() B) array_shift() C) unset() D) array_splice()

18. What is the primary difference between `unset($array[key])` and `array_pop($array)`?

A) `unset` removes from the beginning, `array_pop` removes from the end. B) `unset` removes a specific element, `array_pop` specifically removes the last element. C) `unset` returns the removed value, `array_pop` does not. D) There is no functional difference.

19. Which function merges one or more arrays together?

A) array_combine() B) array_merge() C) array_replace() D) array_union()

20. Consider `$array1 = [1, 2]; $array2 = [3, 4];`. What is the result of `array_merge($array1, $array2)`?

A) [1, 2, 3, 4] B) [[1, 2], [3, 4]] C) Error: Cannot merge arrays. D) [0 => 1, 1 => 2, 0 => 3, 1 => 4]

21. What happens if `array_merge()` is used with associative arrays having the same keys?

A) The values from the later array overwrite the values from the earlier array. B) An error is generated. C) The keys are numerically indexed. D) The duplicate keys are ignored.

22. Which function creates an array using one array for keys and another for values?

A) array_merge() B) array_combine() C) array_keys() D) array_values()

23. For `array_combine()`, what is a crucial requirement for the input arrays?

A) They must be indexed arrays. B) They must have the same number of elements. C) The value array must contain unique elements. D) The key array must contain string values only.

24. What is the purpose of `count($array)` or `sizeof($array)`?

A) To get the value of the first element. B) To get the number of elements in the array. C) To sort the array. D) To check if the array is empty.

25. Which function returns an array containing all the keys of an array?

A) array_values() B) array_keys() C) array_search() D) array_key_exists()

26. Which function returns an array containing all the values of an array?

A) array_keys() B) array_values() C) array_search() D) implode()

27. What does `in_array($needle, $haystack)` do?

A) Returns the key of the first occurrence of a value in an array. B) Checks if a value exists in an array. C) Returns the value associated with a given key. D) Checks if a key exists in an array.

28. Which function searches an array for a given value and returns the corresponding key if successful?

A) array_key_exists() B) in_array() C) array_search() D) key_exists()

29. What is the return value of `array_search()` if the value is not found in the array?

A) NULL B) FALSE C) An empty string D) 0

30. Which function checks if a key or index exists in an array?

A) in_array() B) isset() C) array_key_exists() D) key_exists()

31. Consider `$data = ['a' => 1, 'b' => 2];`. What does `array_key_exists('a', $data)` return?

A) 1 B) TRUE C) 'a' D) NULL

32. What is the difference between `isset($array['key'])` and `array_key_exists('key', $array)`?

A) `isset` returns NULL if the key doesn't exist, `array_key_exists` returns FALSE. B) `isset` checks if the key exists AND its value is not NULL, `array_key_exists` only checks for existence. C) `array_key_exists` is faster. D) There is no significant difference in modern PHP versions.

33. Which function sorts an array by its values in ascending order, maintaining key association?

A) sort() B) asort() C) ksort() D) rsort()

34. What is the primary difference between `sort()` and `asort()`?

A) `sort` sorts by keys, `asort` sorts by values. B) `sort` re-indexes numerically, `asort` maintains original keys. C) `sort` sorts in descending order, `asort` in ascending. D) There is no difference.

35. Which function sorts an array by its keys in ascending order?

A) asort() B) ksort() C) sort() D) krsort()

36. What does `rsort()` do to an array?

A) Sorts values in ascending order, re-indexing numerically. B) Sorts values in descending order, re-indexing numerically. C) Sorts keys in ascending order. D) Sorts keys in descending order.

37. Which function sorts an associative array in reverse order according to its values?

A) arsort() B) krsort() C) rsort() D) sort()

38. What is the purpose of `array_slice($array, $offset, $length)`?

A) To remove elements from an array. B) To extract a portion of an array into a new array. C) To insert elements into an array. D) To flatten a multi-dimensional array.

39. When using `array_slice()` with a negative `$offset`, what does it indicate?

A) The slice starts from the beginning of the array. B) The slice starts from the end of the array. C) An error will occur. D) The slice will be empty.

40. What is the default value for the `$length` parameter in `array_slice()` if omitted?

A) 0 B) 1 C) The remaining elements from the offset D) The total number of elements in the array

41. Which function is used to split a string into an array by a string separator?

A) implode() B) explode() C) str_split() D) chunk_split()

42. What does `implode('_', $array)` do?

A) Splits the array into smaller arrays. B) Joins array elements into a string using '_' as a separator. C) Creates a new array with reversed elements. D) Returns the number of elements in the array.

43. Consider `$arr = ['apple', 'banana', 'cherry'];`. What is the result of `implode(', ', $arr)`?

A) 'apple', 'banana', 'cherry' B) ['apple', 'banana', 'cherry'] C) 'apple, banana, cherry' D) Error: Cannot implode.

44. What is a multi-dimensional array in PHP?

A) An array containing only strings. B) An array where each element is itself an array. C) An array with more than 100 elements. D) An array sorted alphabetically.

45. How would you access the value 'banana' in the following multi-dimensional array: `$fruits = [['apple', 'banana'], ['cherry', 'date']];`?

A) $fruits[1][0] B) $fruits[0][1] C) $fruits['fruit'][1] D) $fruits[0]['banana']

46. Which PHP function is used to recursively sort an array by values, maintaining key association?

A) sort() B) asort() C) ksort() D) usort()

47. What is the primary use case for `array_splice()`?

A) To add elements to the beginning or end of an array. B) To remove and/or replace existing elements with new ones in an array. C) To merge two arrays into one. D) To create a copy of an array.

48. If you need to sort an array based on a custom comparison of values using a user-defined function, which sorting function should you use?

A) sort() B) asort() C) ksort() D) usort()

49. What does the `range()` function create in PHP?

A) A random sequence of numbers. B) An array containing a range of elements. C) A string from an array. D) A multi-dimensional array.

Arrays - indexed and associative arrays, looping arrays, array operations - Online Test

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